Relining pipe having pipe elements interconnected by pipe couplings

ABSTRACT

A relining pipe for insertion inside sewer lines to repair them. The relining pipe is made up of a number of substantially rigid pipe elements (1), which are interconnected by pipe couplings, the pipe coupling including a female sleeve part (2) and a male locking part (3), at least one of these having a circumferential shoulder surface and the other having a stop surface pressing against the shoulder surface when the pipe elements are pressed against each other, and in the female part and the male part counterparts (5, 16) which snap-lock to each other in order to prevent the pipe elements from becoming detached from each other. The pipe element (1) has, as an extension of the male part (3) towards the female part (2), a shoulder ring (6) which is integral with the element and the outer diameter (D3) of which is approximately the same as the outer diameter (D2) of the female part. This shoulder ring has a shoulder surface (7) against which the stop surface of the outer edge of the female part (2) presses when the pipes are pressed together.

TECHNICAL FIELD

The invention relates to a relining pipe for insertion into a sewer lineand similar pipelines to repair them, the relining pipe being made up ofa number of substantially rigid pipe elements which are interconnectedby pipe couplings, such coupling comprising a female sleeve part, theouter diameter of which is greater than that of the pipe part, and amale locking part, at least one of them having a circumferentialshoulder surface transverse to the pipe length and the other having atransverse circumferential stop surface pressing against the shoulderwhen the pipe elements are pushed against each other, wherein in thebottom of the female part and at the outer end of the male part thereare counterparts which snap lock to each other in order to prevent thepipe elements from being detached from each other under tension.

BACKGROUND ART

Many, for example, buried pipelines, such as sewer lines, and amongthese in particular concrete sewer pipes, deteriorate gradually, and forvarious reasons also other damage may appear in them, such as cracks,ruptures, and the like. At some stage the pipelines in use must berepaired. This can, of course, in the case of sewer lines be done bydigging them up and by replacing them with new pipes. However, theexcavation and filling work is expensive and time-consuming, andadditionally the excavations cause disturbance to traffic, for examplein cities. For this reason, damaged pipelines are now being repaired bymeans of so-called relining pipes which are, for example, plastic pipeswhich are inserted from the end of the pipeline section to be repairedinto the original pipe, whereby the original pipe is lined inside.

There are several types of such relining pipes. One possibility is touse flexible, for example corrugated, plastic piping, the parts of whichare interconnected by welding above ground and the pipe is inserted in acontinuous form, for example, through a manhole, into the pipelinesection to be repaired. Such piping is inexpensive, but it can be usedonly in relatively small diameters, since a large-diameter pipe cannotflex in the small space of a manhole. In addition, in such a pipestructure it is difficult to arrange a branching system which could beimplemented without opening the intersection area.

Another possibility is to use pipe elements the length of which is atmaximum the diameter of a manhole, in which case the pipe elements canbe inserted one at a time to extend a pipe element or a row of pipeelements already in the sewer line section, and this relining pipe madeup of pipe elements is inserted always one element length at a time intothe sewer line section being repaired. One possibility for forming suchpipe elements is to cast or otherwise form tubular pieces having femalesleeves at both ends. In addition, in this embodiment male pipe lengthsare used the length of which corresponds to the length of twosuccessively placed sleeve parts. In this case, the outermost ends ofthe female parts will settle against each other and the pipe lengthinside them will keep the ends of the elements in place. This reliningpipe is thicker at the female parts than elsewhere. However, thisstructure has the disadvantage that counter-surfaces which bear thecompression force generated between the pipe elements when they arebeing inserted into the sewer consist only of the said female-part ends,i.e. one point. In the contact point area of the pipe length and thebase of the female part there are no surfaces resisting the push, and sothe pipe length may slide through the female part to the inside of theelement, thereby damaging the structure. Furthermore, this constructionhas no tension-resistent shaping by means of which the elements becomingdetached from each other would be prevented if they for some reason haveto be pulled backwards even over a small distance. The result may be apipe lining having one or more detached joints at unknown locations, inwhich case the relining is to be deemed a failure.

Another relining-pipe structure is made up of elements which wereoriginally formed from extruded piping by cutting it into suitablelengths and by machining at one end of each of the elements thusobtained a female sleeve part and at the other end a male locking part.In this known structure there are, in the outer edge of the male lockingpart and in the bottom of the female part, snap-locking counterpartswhich will prevent the pipe elements from becoming detached from eachother under tension. In addition, in this structure it is relativelyeasy to produce two sets of counter-surfaces resisting pressure,whereupon the couplings between the pipe elements will withstand pushingrelatively well. However, this structure is expensive, since the pipehas to be extruded so as to have very thick walls in order to enable asufficiently sturdy female sleeve part and a male locking part to bemachined in it. In this case the material costs are very high. Inaddition, the manufacture of the female part and the male part entirelyby machining increases the price and occasionally causes dimensionalerrors. These dimensional errors in the female part or the male partcomplicate installation, or sometimes even make it impossible. On theother hand, if the extruded pipe were made with thinner walls, the wallof the female part and the wall of the male part would be so thin thatthe joint would break when the pipes are pressed together. In thisalternative the relining pipe in its entirety has a smooth exteriorsurface.

DISCLOSURE OF THE INVENTION

The object of the invention is to provide, for the forming of a reliningpipe, elements with a relatively small wall thickness. In other words,the purpose is to provide pipe elements which do not have excessivematerial considering the requirements of the functioning of the reliningpipe during use. Another object of the invention is to provide pipeelements of this type, which can be coupled successively and whichthereupon have sufficient counter-surface areas to withstand theconsiderable compressive force the coupling is subjected to at the timethe relining pipe is being inserted. This compressive force is due tothe fact that the length of the pipe section to be inserted may be up to300 meters, lengths of 50 meters being very common, and there may becurvature in these sections. Thus the coupling between the last pipeelement and the previous pipe element is subjected to the resistancecaused by the friction between the entire relining-pipe section and thesewer wall. It is a third object of the invention to provide a reliningpipe of this type, made up of pipe elements, with the friction betweenits outer surface and, for example, a sewer wall being minimal in orderto minimize said compressive force caused by friction. It is a furtherobject of the invention to provide a pipe element of this type, withminimized possibility for dimensional errors and consequent installationproblems.

The problems described above can be solved and the objects defined abovecan be achieved by means of a relining pipe according to the invention.

The most important advantage of the invention is that the material costsof the pipe are very low, and that the elements can be manufactured by atechnique in which there is hardly any possibility for dimensionalerrors. It is a further advantage of the invention that the couplingsbetween the elements withstand very sturdily both compressive andtensile forces, and that the friction of the outer surface of a reliningpipe made up of the pipe elements in, for example, a sewer line, is low.

The invention is described below in detail, with reference to theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The figure depicts a side view, partly cutaway, of a relining-pipeelement according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The figure shows a relining-pipe element 1 which has a relatively thinpipe part 4 wall 18, the thickness of which has been dimensioned so asto be just sufficient to function as an installed lining and towithstand the compression caused by the insertion. At one end of thispipe element 1 there is a female sleeve part, the outer diameter D2 ofwhich is greater than the outer diameter D1 of the pipe part 4, and atthe other end a male locking part 3. In the bottom of the female part 2and at the outer end of the male part 3 there are locking ring 5 andlocking groove 16 which snap lock to each other, preventing the pipeelements from being detached from each other when pulled. According tothe invention, the pipe element has, as an extension of the male lockingpart 3, a shoulder ring 6 which is integral with the element, thisshoulder ring being at that edge of the locking part which faces thepipe part 4 and the female part 2. The outer diameter D3 of thisshoulder ring 6 is on the same order of magnitude as the outer diameterof the female part, and this shoulder ring has, facing the locking part,a shoulder surface 7 transverse to the length L of the pipe. The outeredge of the female part 2 forms a stop surface 8 transverse to thelength L of the pipe. When, at the time a coupling is being formed, themale part 3 pushes inside the female part 2, the shoulder surface 7,which is on that side of the shoulder ring 6 which faces the male part,will settle against the stop surface 8 of the female part 2. Thereby onesturdy surface pair is formed to resist compressive force.

As an extension of the female part 2 towards the male part 1 there is alimiting ring 9, which is also integral with the element. Between thislimiting ring 9 and the female part there is a circumferential groove 10which has side surfaces 11a and 11b transverse to the length L of thepipe. The groove 10 extends from the outside approximately to the levelof the outer surface 14 of the pipe part 4. This groove 10 is for alocking chock, which is used when interconnecting the relining-pipeelements. When most of the latest relining-pipe element, specificallythe male locking part 3 first, has been inserted into the sewer pipe tobe repaired, a flat locking chuck is inserted into this groove 10, intowhich it fits with relative precision. Thereafter, the nextrelining-pipe element is placed as a continuation of thisabove-mentioned element, and the male part of the latter element ispushed into the female part of the preceding element by means of, forexample, a hydraulic cylinder. Thereupon the locking chuck will settleagainst the manhole wall, thus preventing the movement of the alreadyinserted relining-pipe section in the direction of the sewer bysupporting the pipe via this groove 10.

Both the shoulder ring 6 surface 12 which faces away from the malelocking part 3 and the limiting ring 9 surface 13 which faces away fromthe female part 2 are beveled. Each of said surfaces 12 and 13 forms anangle K1 and respectively K2 relative to the outer surface 14 of thepipe part 4, the angles being at minimum of approx. 120°, and preferablyat minimum of 135°. These angles K1 and K2 may be mutually equal orunequal, and an angle value in the order of approx. 150° has beenobserved to be especially advantageous; such angles are shown in theembodiment of the figure. In this case, the relining pipe will be incontact with the wall of the sewer being repaired over a length somewhatgreater than the length of the female part, and since the outward-facingedge surfaces 12 and 13 of this section are sufficiently beveled, thisprotruding section, the diameter of which is D2, cannot foul onanything, and the resistance to push is very small.

In order to provide the snap locking, there is provided on the outeredge of the male part 3 a locking ring 5 equipped with an outwardlybeveled surface 15a and a surface 15b which faces the pipe part 4 and istransverse to the pipe length L. This outwardly beveled surface 15a thusconstitutes part of a conical surface the tip of which points in thesame direction as the male part, in order that the locking ring wouldpush with sufficiently low resistance into the female part. In thebottom of the female part 2 there is a locking groove 16 having agreater diameter than the inner diameter D4 of the rest of the femalepart, the groove having a stop surface 17a facing the outer edge of thefemale part, and the transverse surface 15b of the locking ring 5engaging behind it in order to prevent the locking ring of a secondpipe, and thereby the entire pipe, from being detached from the firstfemale part and the corresponding pipe. The bottom of the locking groove16, i.e. the side surface facing away from the outer edge of the femalepart, is preferably shaped as a shoulder 17b transverse to the length Lof the pipe element. The section 15c from the beveling 15a of the outeredge of the locking ring 5 towards the center line of the pipe is also atransverse stop surface. This section 15c presses against the shoulder17b of the female part when the male part is pressed into the femalepart, whereby a second surface pair withstanding the pressure betweenthe pipe elements is formed. The length H1 of the locking groove 16 inthe longitudinal direction L of the pipe is arranged to be greater thanthe thickness H2 of the locking ring 5 in the same direction, whereby asmall angular difference between successive relining-pipe elements ismade possible. This angular difference, in turn, enables a relining pipemade up of pipe elements to be inserted into a curved sewer or the like.The male part additionally has a groove for a sealing 19, which sealssuccessive pipe elements to each other in a manner known per se.

I claim:
 1. A relining pipe for insertion inside sewer lines and similarpipelines in order to repair them, which comprises:a plurality ofsubstantially rigid pipe elements (1) a coupling interconnecting saidpipe elements, said coupling having a female sleeve part (2) the outerdiameter (D2) of which is greater than the outer diameter (D1) of a wallof the pipe elements, and a male locking part (3) wherein a bottom ofthe female part and the outer end of the male part have counterparts (5,16) which snap-lock to each other in order to prevent the pipe elementsfrom being detached from each other under tension; the pipe elementseach having (1), as an extension of the male locking part (3), anintegral shoulder ring (6) wherein the outer diameter (D3) of theshoulder ring is substantially the same as the outer diameter (D2) ofthe female part, and which has a shoulder surface (7) transverse to alength (L) dimension of the pipe element, a stop surface (8) formed bythe outer edge of the female part pressing against said shoulder surface(7) when the pipe elements are pressed together, thereby forming a firstsupport surface pair, wherein the bottom of the female part (2) is ashoulder (17b) transverse to the length of each of said pipe elements,and wherein a stop surface (15c) formed by the outer edge of the malepart (3) presses against said shoulder surface (17b) when the pipeelements are pressed together, thereby forming a second support surfacepair.
 2. A relining pipe according to claim 1, wherein each of the pipeelements (1) has, as an extension of the female part (2) towards thelocking part (3), an integral limiting ring (9); wherein between saidlimiting ring and the female part a groove (10) is positioned, thegroove having side surfaces (11a, 11b) transverse to the pipe length (L)and the groove extending approximately to the level of an outer surface(14) of the wall of each of the elements, and wherein the shoulder ring(6) is located on each of the pipe elements at a point towards thefemale part (2) from the male part (3).
 3. A relining pipe according toclaim 1 or 2, wherein the shoulder ring (6) surface (12) facing awayfrom the male locking part (3) and the limiting ring (9) surface (13)facing away from the female part (2) are beveled in such a manner thateach of the said surfaces (12, 13) forms an angle (K1 and K2) to theouter surface (14) of each of the pipe elements, the angles being at aminimum substantially 120° in order to ensure the movability of therelining pipe.
 4. A relining pipe according to claims 1 or 2, whereinthe outer edge of the locking part (3) has a locking ring (5) providedwith an outwardly beveled surface (15a) and a surface (15b) facing thepipe part (4) and transverse to the pipe length (L), and the bottom ofthe female part 2 has a locking groove (16) having a greater diameterthan the inner diameter (D4) of the rest of the female part, the lockinggroove having in its outer edge a transverse stop surface (17a) forproviding the snap-locking, wherein the bottom of the locking groovecomprises said transverse shoulder (17b) and the section from thebeveling (15a) of the locking ring (5) towards the center line of thepipe comprises the stop surface (15c), and wherein the length (H1) ofthe locking groove (16) in the longitudinal direction (L) of the pipe issubstantially greater than the thickness (H2) of the locking ring in thesame direction.
 5. A relining pipe according to claims 1 or 2, whereinthe pipe elements (1) comprise extruded plastic pieces.